NGC 6871 (Lund 921, Cr 413) and Biurakan 1(Lund 922) Open Clusters in Cygnus

Center of field at approximately: RA 20 hours 06 minutes 46 seconds, Dec +35 degrees 44 minutes 14 seconds

Size: 20' (30') and 14' (10') Magnitude: 5.2 and -- Class: II 2 p n and IV 3 p n

North is up

West to the right

Telescope:

8" f5 Newtonian reflector

Camera:

 ST-8XME, self-guided, binned 1x1, temp -20c, camera control MaxIm DL 4.56

Image:

Lumicon Red filter, 240 minutes (24 x 10 minute subs), 08/18/19/2008; seeing 2.7-3.2 FWHM per CCDStack

Processing:

CCDStack 1.3.7, Photoshop 7.0

Location:

 Rolling Roof Observatory, Thousand Oaks, CA 91360 (+34d 13m 29s -118h 52m 20s)

Notes: Decided to re-image this field (old image was 170 minutes, Deep Sky filter, 08/24/2007) for better centering between the two clusters, and better collimation.

Comments from "Star Clusters", by Brent Archinal and Steven Hynes; NGC 6871 is "about a dozen bright stars over a 30' field of rich Milky Way". Biurakan 1 is "Archinal: Id? Rich field around bright star, but no obvious cluster on DSS image". According to "Star Clusters", NGC 6871 is 30 arc minutes in size, and Biurakan 1 is 10 arc minutes in size.

 This area is about 5.5 degrees SSW from Sadr, the center of the Swan, and is laced with the faint nebulosity that pervades central Cygnus. This field is just barely 21 minutes north of B 147, which I imaged 08/26/27/28/2007. See that image for more details on this area.

From the NGC / IC Project:

Contemporary Visual Observation(s) for NGC 6871
NGC 6871 = Cr 413 = Lund 921 = OCL-148
20 05 59.4 +35 46 38
V = 5.2;  Size 20

13.1": dominated by two bright multiple stars (6.8/7.4 at 34" with four 
additional close companions and 7.9/8.8.9 pair at 20" surrounded by several mag 
11 stars).  The bright pairs are oriented N-S and separated by about 2'.  
Situated in a very rich star field.  The cluster itself is in a bright, rich 
field with no apparent boundaries.

8": two sets of multiple stars in a very rich field including ?440 = mag 7, 12, 
11, 9.5, 11.5, 8 at 7", 11", 11", 28" and 36".  Located 13' SW of a mag 5.5 
star.

- by Steve Gottlieb